1. Field of the Invention
The present invention relates to an optical device for aligning liquid crystal molecules at an angle and to a method of fabricating this optical device. The invention also relates to a liquid crystal display using this optical device.
2. Description of the Related Art
Known optical devices incorporated in liquid crystal displays are optical devices made of polymerizable liquid crystal materials. These elements are widely used in absorptive circularly polarizing plates (λ/4 retardation layer and λ/2 retardation layer) forming liquid crystal displays. Furthermore, they are widely used as linearly polarizing plates and as viewing angle-compensating layers of various liquid crystal modes.
For example, it is known that in an ECB mode liquid crystal display, a wide viewing angle is obtained by aligning liquid crystal molecules at an angle to form an optical device of a so-called hybrid structure as a retardation layer. That is, the phase difference of the optical device (retardation layer) in which the liquid crystal molecules are aligned at an angle has dependence on the viewing angle. Therefore, a wide viewing angle can be secured by combining optical devices (retardation layers) of a hybrid structure of a phase difference having given dependence on the viewing angle so as to cancel out the residual phase difference of the liquid crystal layer LC when black is exhibited by the ECB mode liquid crystal cell and constructing a liquid crystal display.
Such a retardation layer (optical device) is formed by applying compositions including a polymerizable liquid crystal compound or surface active agent onto a substrate and then polymerizing the polymerizable liquid crystal compound by light irradiation or heating. Furthermore, a polymerizable liquid crystal compound has been proposed which has compositions whose viscosities are kept high to permit the compositions to be applied over a large area uniformly and easily. This compound does not easily crystallize if allowed to stand at room temperature (see JP-A-2005-272560 (patent document 1)).